Martin
1244 posts
Sep 02, 2017
6:50 AM
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In my frustration over bad amplifier sound, for an upcoming practice session with a blues band I´m only going to equip myself with a Joyo American Sound, and/or a Harp Attack. Perhaps a delay as well.
When lining out such pedals, is it OK to use standard guitar cables and go to "line" on the board, or should I use the PA:s XLR connections?
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hvyj
3472 posts
Sep 02, 2017
7:16 AM
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The 1/4" inputs on the PA board bypass the board's mic preamps. The XLR inputs do not.
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dougharps
1548 posts
Sep 02, 2017
7:16 AM
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Edited to remove possible "brain dump".
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Doug S.
Last Edited by dougharps on Sep 04, 2017 12:07 PM
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AppalachiaBlues
47 posts
Sep 02, 2017
7:26 AM
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I have found the best approach is to run the pedals into a DI box, then go into the mixing board or PA with a balanced XLR line. This is what I do, using a LW Harp Attack and delay pedal.
In the past I have used a standard guitar cable straight in. Sometimes it worked fine, other times there were issues. One time, I believe it damaged a mixing board, though the sound man never clearly confirmed that to me. Since starting to use the DI box and XLR cable, I have no risks and no surprises - one less thing to worry about.
Last Edited by AppalachiaBlues on Sep 02, 2017 7:28 AM
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Martin
1245 posts
Sep 02, 2017
11:26 AM
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@hvyj: "The 1/4" inputs on the PA board bypass the board's mic preamps. The XLR inputs do not."
Is that a good thing, to bypass the mic preamps?
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Martin
1246 posts
Sep 02, 2017
11:29 AM
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OK, since I don´t have a DI box (yet), I guess it´s touch and go with whatever cables I have at hand ...
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timeistight
2183 posts
Sep 02, 2017
12:00 PM
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If the mixer has channel inserts you could run your low impedance microphone into a mic input and run the pedals in the insert.
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Martin
1247 posts
Sep 02, 2017
12:50 PM
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@timeistight: OK thank you. Not sure I get that, but I hope some of the other fellas are a little more tech savy than I.
I wonder, is it somehow "wrong" to run a, say SM57 straight to a PA? These issues are confounding me more and more ...
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timeistight
2184 posts
Sep 02, 2017
1:17 PM
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'I wonder, is it somehow "wrong" to run a, say SM57 straight to a PA?'
Of course not. That's what they are designed to do.
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AppalachiaBlues
50 posts
Sep 02, 2017
1:25 PM
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Martin, its not "wrong" to run an SM57 straight into a PA with an XLR cable -- in fact that is exactly how it is designed to be used. I do that when playing "acoustic" harp with the mic on a stand, or when singing.
However, if you want to play cupped, the sound will stay pretty clean unless you're really good at cupping. The PA is faithful to what you feed it, and the SM57 in most hands is a pretty clean mic. So if you want a thick and dirty sound, like the breakup of a tube/valve amp... then you need your Harp Attack and/or Joyo to alter the signal before it goes into the PA.
This brings you back to the question of: straight in with a guitar cable, or tamed with DI box into an XLR cable? With the pedals in the chain, the DI is a good idea.
Last Edited by AppalachiaBlues on Sep 02, 2017 1:28 PM
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AppalachiaBlues
51 posts
Sep 02, 2017
1:30 PM
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It also depends on the length of the cable run. A 1 to 3 meter guitar cable might work fine. But if you need a 15 to 20 meter run, better to do that with an XLR cable.
Last Edited by AppalachiaBlues on Sep 02, 2017 1:39 PM
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hvyj
3475 posts
Sep 02, 2017
1:51 PM
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@Martin: Well, I prefer not to bypass the mic preamps, but it's not a bad thing per se.
The more relevant question is why you need these pedals running into a board. I assume the board has reverb or delay on it. It should also have eq. Try this: treble at 9 or 10 o'clock. Bass at noon or 1. Mids somewhere between noon and 2:30. Then, for dirt, increase the gain or pad (whatever it's called on this particular board) SLIGHTLY. Be careful with this or you will feedback and you may need to back off a little on the volume control to compensate. But go slightly above unity gain setting. Doing that and cupping your SM57 tight will give you dirt. Then fiddle with the tone controls to get the timbre dialed in. Run the mic into the PA with an XLR cable, and use the verb on the board.
Last Edited by hvyj on Sep 02, 2017 1:58 PM
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Joe_L
2772 posts
Sep 02, 2017
5:01 PM
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There is nothing wrong with plugging the SM57 directly into the PA. Based on your other thread, I would do this and not use the pedals. It will reproduce your sound pretty accurately. You will know pretty quickly if the tone challenges you face are equipment related or not. Get to the bottom of that before you start playing with pedals.
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MindTheGap
2326 posts
Sep 03, 2017
1:09 AM
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The issue is about the signal level. A typical 'line' input is expecting a higher signal level that you get from a guitar, or your normal pedals. In which case your output volume may be too quiet.
However, your Joyo box has an unusually wide output range, and I have found it can match anything to anything (e.g. acoustic guitar with piezo pickups to line, CBG with 'unknown output level' to amp or PA etc.) As long as you like the sound of the Joyo, and know how to set it so it's not just a fuzzbox, it's a useful general purpose device.
Of course to use it in that way, you need the Joyo at the end of the chain before the PA.
That said, I agree with the above advice that the 'proper' way to do it is with a DI box. That will match your signal level to what the PA expects, and allows long cable runs.
Last Edited by MindTheGap on Sep 03, 2017 1:14 AM
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Martin
1248 posts
Sep 03, 2017
6:22 AM
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OK, a DI box is an impedance transformer, right? And I need that (with implied qualifications on "need") if I use a lo-Z mic.
Should I then go through the IMT first, and then to the pedal(s), or other way around?
@hvyj: You remember from another tread that I was not completely satisfied with the sound from my amp. (And I´m going to address that in the near future.)
Why I need the Joyo pedal is as a (temporary) substitute for the amp -- the same way people use the Harp Attack: You can do more with the sound in terms of colouring etc. I´ve played direct to to PA´s many times and some times it have sounded good and sometimes not. (Depending on the quality of mic and of the PA: with my recently deceased Beyerdynamic M160 it could sound excellent.)
If you´re with a loud and rowdy blues band with two guitars you need a bit more grit than what a PA can provide. Hence the pedal.
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Martin
1249 posts
Sep 03, 2017
6:44 AM
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@Apalachiablues: Sorry, I see now you have answered my question above.
As an aside, this one was made with my cheap SM57 copy into the Joyo into a PA. But circumstances were very controlled in a small room -- and I could not go high in volume:
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timeistight
2185 posts
Sep 03, 2017
7:09 AM
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No you can run your low-impedance mic directly into the low-impedance input on the PA. However, if you wish to use your high-impedance pedals before going to the PA, you should use a low-to-high transformer at the input of the first pedal and a high-to-low (i.e., DI) transformer at the out put of the last pedal in the chain. Lone Wolf makes a box called the Front Man that combines both function with a switch that lets you switch all your pedal in and out at once.
As I wrote earlier, you could avoid all this transforming back and forth by running the mic direct to the PA low-impedance input, giving your pedals to the sound man, and asking him to put them in your channel insert.
I should also point out that you need a proper balanced low-impedance cable with XLR jacks at both ends between your mic and the PA input if you go that route. Don't try to use your jury-rigged "adapter" cable.
Last Edited by timeistight on Sep 03, 2017 7:47 AM
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dougharps
1549 posts
Sep 03, 2017
7:15 AM
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Edited to remove possible "brain dump".
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Doug S.
Last Edited by dougharps on Sep 04, 2017 12:06 PM
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MindTheGap
2327 posts
Sep 03, 2017
11:01 AM
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As I've mentioned before, the purpose of the IMT is not to match the mic and amp impedance. In fact that's a thing it specifically doesn't do. The purpose of the IMT is to convert between balanced and unbalanced audio schemes - which involves different signal levels and wiring, and incidentally the source impedance. I agree the name is misleading, it's better called a 'Balun', but IMT is what it's called in the shops.
Martin, you can probably achieve what you want without buying any extra kit. However, it involves some understanding of the underlying electronics principles to get a good result. On balance, I agree with the comments here that you should take the conventional route. Get an IMT and a DI box and then every sound person you meet will know what to do. You tell them you want to go through the PA and they will wave an XLR cable in your face. You plug that into your DI box and entertain the audience with your good harp playing. No mess, no fuss.
Last Edited by MindTheGap on Sep 03, 2017 11:12 AM
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dougharps
1553 posts
Sep 03, 2017
11:30 AM
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@MindTheGap
Please clarify, or provide a link to the thread in which you explained it.
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Doug S.
Last Edited by dougharps on Sep 04, 2017 12:10 PM
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MindTheGap
2328 posts
Sep 03, 2017
11:57 AM
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It's true that it does change the mic impedance, but that's incidental really. Here's the thread, if you search for 'bridging' on the page that's part of the discussion. Hope that helps.
http://www.modernbluesharmonica.com/board/board_topic/5560960/5496590.htm
I agree with all the other things you wrote above. That's good practical advice, and I think Martin should do that. Then he doesn't have to worry about the thing, it will just work.
Last Edited by MindTheGap on Sep 03, 2017 12:02 PM
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Martin
1250 posts
Sep 03, 2017
3:27 PM
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OK, I see that this is beginning to overlap with another tread, that I also started.
This, in all its facets, is enormously much more complicated that I thought, and I must seek professional help of the hand-holding kind.
I´m going to get that DI box, but as a start I´ll have to make do with what I´ve got in terms of pedals and cables and try out the PA that´s in this rehearsing room.
I thank you all for suggestions and input.
(The musical example was just to show a kind of sound that I don´t think can be achieved with playing straight through an SM57 into a PA, as a comment to what hvyj suggested. On the other hand, that kind of distortion is very hard to get in a live situation as well, that much I know ...)
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timeistight
2186 posts
Sep 03, 2017
10:44 PM
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"This, in all its facets, is enormously much more complicated that I thought"
It's not, really. You just need to match your outputs and inputs: put high-impedance, unbalanced outputs into high-impedance, unbalanced inputs and put low-impedance, balanced outputs into low-impedance, balanced inputs. If you have an output and an input that don't match then you need a widget to go between them to make things work.
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MindTheGap
2329 posts
Sep 03, 2017
11:05 PM
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I agree with that. If you go the conventional route, then it's simple.
Yes indeed this thread overlaps with the other one, as it's the same question, at bottom. The thing I'm pushing back against is the notion that it's 'wrong' to do such-and-such. In that sense it's definitely 'wrong' to cup a mic and harp together! Despite that, it can sound quite good.
If you can get the sound you want out of your mic into a pedal without an IMT (wrong!), and get the right signal level into the 'line' input of a PA (wrong!) using a long guitar cable (wrong!) then who cares. This isn't guesswork, there's perfectly good technical reasons why this can work, outlined in this and the other thread.
But IMO you should definitely follow the advice above and get an IMT and DI box and bask in the glow of knowing you are conventional. I look forward to you NOT doing that, and still getting the sound you like :)
Isn't that the whole history of the harp?
If only someone had told Snooky Pryor not to play his harp through the army camp PA (for that is the fable/story/fact), clearly so very wrong, then none of us would have to bother with any of this stuff.
Last Edited by MindTheGap on Sep 04, 2017 6:34 AM
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dougharps
1554 posts
Sep 04, 2017
8:43 AM
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@MindTheGap
Thanks for the link you posted in response to my request.
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Doug S.
Last Edited by dougharps on Sep 04, 2017 12:11 PM
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timeistight
2188 posts
Sep 04, 2017
9:49 AM
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You know, given that Martin is new to all this, I don't think it's helpful to do brain dumps of every conceivable sound reinforcement scenario. He's confused enough already.
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dougharps
1555 posts
Sep 04, 2017
11:27 AM
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@ timeistight
Thanks for the heads up.
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Doug S.
Last Edited by dougharps on Sep 04, 2017 12:04 PM
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Martin
1251 posts
Sep 04, 2017
12:27 PM
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@timeistight: "You know, given that Martin is new to all this, I don't think it's helpful to do brain dumps of every conceivable sound reinforcement scenario. He's confused enough already."
Thanks for the consideration. "New" could be slightly modified -- I´m 60 and I´ve been playing a while ... but certainly new to electronic technicalities. It may seem weird that I don´t know more about these things, but I´ve plugged in and played -- used to be mostly with a Green Bullet and various amps -- and never given much thought to impedances and such.
And, interestingly, I´ve never heard it spoken of in harmonica amplification contexts. Until very recently.
I´m priveliged to such an extent that I have a couple of guys that I can pass on all your tips to, and thus get some kindergarten schooling; also, one of them is building me a DI box that I hope will help me some.
But as Already Aristotle remarked, there is no Royal Road to knowledge.
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1847
4422 posts
Sep 04, 2017
2:48 PM
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martin... did you check out hakan's video?
he is using a low impedance mic .... he installed a transformer inside of the mic.
pretty simple and inexpensive to do.
he is also using a 5 watt amp with an 8 inch speaker. it does not sound metallic to my ears.
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Martin
1252 posts
Sep 05, 2017
5:40 AM
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@1847: Yes I did, but perhaps I´d go for the description "harsh", as per another tread, where I sought advice on how to avoid sounding "harsh and metallic".
I´m not terribly wild about that sound, but it works. (And I know many of you blues guys find it stupendous.) Question is, at what volume does it work?
"Installing a transformer inside of a mic" ... Hm, you could just as well ask me to build an exact copy of Apollo 11. But I hear that Håkan sometimes frequents a blues jam here in Gothenburg and I´ll make sure to ask him if I run in to him. (I´m not proud of being a technophobe but it´s a fact of my life.)
As an aside: first time I blew into an amplifier was around 1975. After that I hade a really long hiatus from the harp and didn´t play between 1977 and 1990, but back then I picked up a vocal mic and plugged it in to the only available amp, a Norwegian thing called Vingtor. It sounded great! Not an "impedance" in sight. Perhaps that´s my Freudian dilemma, I hark back to an innocent youth where these things were oh so simple.
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